Automatic renew of vodacom contract

Hi the automatic renewal of Vodacom is *******. I thought that I will automatically go on the pay as you go if my contracts expires on 31/08/19 just to find out today that no still was getting R350 airtime and be changed R370 because I didn't phone vodacom to cancel the contract. And also because it's the 16th today need to give a calendar month notice ( TO A CONTACT THAT ALREADY EXPRICED) and pay for a another month. How is this fair?